Grain-oriented iron and steel and method of making same



D. M. KOHLER GRAIN-ORIENTED IRON AND STEEL AND METHOD OF MAKING SA iEFiled June 28, 1965 SSheets-Sheet 1 Fig. 2

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United States Patent O 3,392,063 GRAIN-ORIENTED IRON AND STEEL ANDMETHOD OF MAKING SAME Dale M. Kohler, Middletown, Ohio, assignor toArmco Steel Corporation, Middletown, Ohio, a corporation of Ohio FiledJune 28, 1955, Ser. No. 467,228 12 Claims. (Cl. 148-12) The inventionrelates to a method of producing oriented iron-base alloys and moreparticularly to a method of making preferred crystallographicorientations in ingot iron and low carbon steel, and the products madethereby.

It has been recognized that all metals and their alloys have some degreeof preferred orientation when rolled and usually a different orientationwhen they are cold worked and recrystallized. When commercial iron andlow carbon steels are rolled into sheets or strips and recrystallizedthey display a weakly developed cubic orientation designated as (100)[011] by Millers indices. This orientation has no particular value inthe present applications of ingot iron and low carbon steels.

Attempts have been made to develop lmore favorable orientations in thismaterial. For example, the initial chemistry of the rnelt has beenvaried by the addition of materials tending to inhibit primary graingrowth. Other methods involving critical strain have been used,entailing varying the method and amount of rolling and heat treatment.Nevertheless prior to this invention the preferred orientations in thenal product were found in only a relatively small number of the grains,perhaps up to as much as of the total grain structure.

Applicant has discovered that ingot iron and low carbon steel can bemade to have at least two highly preferred crystallographic orientationswhich impart useful properties to a polycrystalline sheet or strip.These textures are strong in that more than half of the total grainstructure will have the preferred textures.

By ingot iron and low carbon steel is meant ferrous materials which byladle analysis contain up to about 0.10% carbon, 0.01 to 0.40% manganese(preferably about 0.03 to about 0.12%), up to about 0.05% sulfur, up toabout 0.03% phosphorus, up to about 0.25% copper, the balance being ironexcept for normal amounts of those impurities incident to themanufacture of such material. The ingot iron and low carbon steel mayalso contain a small amount of aluminum. Silicon may also be present asa deoxidizer in small amounts, or additions up to about 1.8% may be madeto increase the Volume resistivity of the product when it is used formagnetic properties. The amount of silicon added may be consistent withthat found in hitherto known non-oriented silicon steels, and isdictated by the phase boundary between alpha iron and gamma iron. Thecarbon and manganese contents will determine whether the material isclassified as ingot iron or low carbon steel, the latter usuallycontaining upwards of 0.05% carbon and 0.20%

manganese.

The two highly preferred crystallographic orientations which ingot ironand low carbon steel may be made to have in accordance with theteachings of this invention are classified by Millers indices as (110)[001] and (112) [110]. The (110) [001] orientation is known ascube-on-edge. As will be described hereinafter, material with thisorientation made from ingot iron and low carbon steel in accordance withthe teachings of this invention will have some magnetic propertiessubstantially as good as or better than those found in 3% orientedsilicon-iron presently in commercial use. Heretofore `it has beenimpossible to obtain highly oriented cube-on-edge "ice low carbon steelor ingot iron without the use of at least 2% silicon.

The (112) [1110] orientation is a form of cube-oncorner texture neverheretofore obtained in substantial proportions in ferrous material. Aswill be described hereinafter material having this orientation and madein accordance with this invention will have good forming properties.

It is therefore an object of the present invention to provide a lowcarbon iron or steel having a high degree of (110) [001] orientation.

It is an object of the present invention to provide a low carbon iron orsteel having a highly developed (112) [110] orientation.

lt is an object of the present invention to provide a method for makinghighly preferred crystallographic orientations in ingot iron and lowcarbon steel.

It is an object of the present invention to provide a method wherebyingot iron and low carbon steel may be made to have a (110) [001]orientation and wherein more than half of the total grain structure willbe characterized by this orientation.

It is an object of the present invention to provide ingot iron and lowcarbon steel with a cube-on-edge orientation and characterized bysuperior magnetic properties.

lt is an object of the present invention to provide ingot iron and lowcarbon steel having a (112) [110] orientation and wherein more than halfof the total grain structure is characterized by this orientation.

It is an object of the present invention to provide ingot iron and lowcarbon steel having a `(112) [110] orientation and characterized by goodformability.

These and other objects of the invention which will be set forthhereinafter or will be apparent to `one skilled in the art upon readingthese speciiications are accomplished by a series of process steps ofwhich certain exemplary embodiments will now be described. Reference ismade to the accompanying drawings wherein:

FIG. l is a photomicrograph at a magnification of 50X showing thepreferred uniform fine-grained structure `of the hot rolled material ofthe present invention.

FIG. 2 is a photomicrograph at a magnification of 5 0 showing the hotrolled material of the present invention with undesirably large grainsat the surfaces.

FIG. 3 is a photomicrograph at a magnication of showing a hot rolledmaterial in which large surface grains such as those illustrated in FIG.2 are not refined and persist after rolling and decaburization.

FIG. 4 is a photomicrograph at a magnification of 100x showing a hotrolled material in which large surface grains are not refined andpersist after cold rolling, decarburization and the final anneal.

FIG. 5 is a photomicrograph at `a magnification of 100x showing thematerial of the present invention after hot rolling, cold Arolling anddecarburization, wherein the grains after hot rolling were in idealcondition.

FIG. 6 is a (100) optical pole figure showing oriented iron having a[001] texture.

FlG. 7 is a (100) optical pole figure showing oriented iron having a(112) [110] texture.

FIG. 8 is a graph comparing the DC magnetization curves for orientedingot iron of the present invention with the curves for conventionalmagnetic ingot iron, nonoriented silicon steel and oriented 3%silicon-iron.

Briefly the invention is based on the discovery that therecrystallization texture of ingot iron and low carbon steel can bechanged by promoting as a final step in the processing the growth ofgrains having the preferred orientations at the expense of grains ofother orientations, a phenomenon referred to as secondaryrecrystallization. In the usual practice the manufacturer of low carbonferrous materials contemplates hot and cold rolling steps to attain adesired final gauge, and an anneal slightly below the A1 or lowercritical temperature to soften the material by recrystallizing the grainstructure. It has been found that subjecting the material during thisfinal anneal to higher 'temperatures or longer times at temperature willtend to increase the grain size, but will have little effect on theorientation of the grains. This is true because the material undergoes aprima-ry recrystallization and an indiscriminate and non-selective graingrowth rather than a secondary recrystallization with selective graingrowth.

A high degree of preferred orientation can be achieved in accordancewith the teachings of this invention by causing sulfur to be diffusedinto the grain boundaries of the primary `grains and thus restrictingtheir growth. This makes possible a secondary recrystallization with theresults above noted.

The ingot iron or low carbon steel may be produced by any of the knownmelting and refining processes. When low carbon steel is used, it may beeither rrimming or killed steel; but, if it is killed steel, siliconkilled steel is preferred. The low carbon iron or steel may be castcontinuously or intermittently into ingots, billets or slabs. It may be4hot rolled to any thickness which the rolling apparatus can produce.Depending upon `the desired cold reduetions which follow the hotrolling, and the desired final gauge of the final product, the hotrolled band may vary in thickness from about 0.125 to about 0.050 inchwith present equipment.

The hot rolling procedure may be varied with regard to the Itemperatureof the stock when it is heated for rolling, when it enters the rollingmill, when it is rolled to various intermediate thicknesses, and when itis cooled to ambient temperatures. These temperatures are wellestablished for ingot iron land low car-bon steel destined forparticular end uses; and these practices can be followed for the,material of the present invention.

It is important, however, that the grain s-ize of the material after hotrolling and before cold rolling be relatively small and uniformthroughout ythe thickness of the material. For this reason the preferredtemperature for finishing the bot rolling of low carbon steels is aboveabout 1600 F. in order to obtain a fine grain structure. Such a desiredfine grain structure is illustrated in the photomicrograph of FIG. 1.Ingot iron will be finished at a lower temperature in the conventionalmanner. Coiling temperatures below 1300 F. are preferred for both ingotiron and low carbon steel to prevent excessive grain growth.

In order to insure a uniform fine `grain structure after hot rolling,the material may be subjected to an open anneal or normalizing heattreatment. While decarburization may be effected during this step, it ispreferred to remove the carbon -at a later stage, as hereinafterdescribed. rIhe principal purpose of the heat treatment following thehot rolling is to refine and equalize the grain structure. This may beaccomplished by a continuous or strand normalizing treatment comprisinga short-time heating above the A3 or upper critical point (about 1625F.). A temperature of about 1800 F. is satisfactory. It has been foundthat if large grains remain at the surface of the material after hotrolling (as shown in FIG. 2), as tends to be the case in the interior ofa coil formed at a relatively high temperature, and if these largegrains are not refined by a high temperature anneal, they will persistthrough a later decarburizing step (see FIG. 3) `and through Ilthe finalanneal (see FIG. 4). FIG. 5 'is a photomicrograph showing the idealgrain structure after decarburization, where the grain structure afterhot rolling was similar to that shown in FIG. 1, or was refined by anormalizing treatment. For reasons of economy, it is preferable toobtain after hot rolling a grain structure of lthe type shown in FIG. 1,thereby eliminating the normalizing step.

It has further been found that initial anneals after hot rolling, whenconducted at temperatures below the upper critical point, have almost noeffect on the grain structure of the material if such an anneal islimited to less than ve minutes. At longer times grain growth anddecarburization occur, and ultimate secondary grain growth becomes moredifficult to achieve.

The ingot iron or low carbon steel having-a lgrain condition similar tothat shown in FIG. 1, is cold rolled in one or more stages to obtain thedesired final gauge. As will be understood by one skilled in the art, asingle stage cold reduction is often preferred for reasons of economy,since multiple stage cold reductions require an anneal between stages.Should multiple'stage cold reductions be necessary, the intermediateanneal should be an open anneal at a temperature between about 1100 F.and about l800 F. in a reducing atmosphere, which may be a decarburizingatmosphere, if pickling is to be avoided. If the atmosphere isoxidizing, pickling will be necessary.

When it is desired that the final product have' a cubeon-edgeorientation, the amount of cold reduction in each stage should be lessthan Reductions of between about 50% and 85% have been foundsatisfactory.

When it is ldesired that the final product have a (112) orientation, thecold reduction should be 90% or more in a single stage process. Withcold reductions of two or more stages, with intermediate anneals, onlythe last cold rolling stage must be 90% or greater. Reductions of 90%have produced excellent results in obtaining a (112) [110] orientationin the final product. The maximum reduction is limited only by thecapacity of the rolling -mill yand the ability `of the material towithstand a drastic deformation.

While the cold reduction ranges given above for obtaining the two typesof grain orientation are fairly precise, the hot rolling conditions,chemistry and final thickness will have some effect on the tendency toproduce secondaries of one kind or the other. I

As stated above decarburization may be carried on prior to the coldrolling. However, it is preferred to decarburize after cold rolling.Decarburization is preferably accomplished by a continuous anneal for a-few minutes in a wet hydrogen-bearing atmosphere at about 1500 F. as isWell known in the art (see U.S. Patent No. 2,307,- 391). The temperaturemay be varied from l200 F. to about l600 F. and less expensivehydrogen-bearing gases such as dissociated ammonia may be used. Thefinal carbon content should be less than 0.01% and for some uses lessthan 0.005%. Decarburization can also be performed in a box anneal.Denitriding to less than .001% nitrogen may also be effected during thedecarburizing anneal or in one of the other annealing treatments.

The final treatment will be a box anneal at a temperature just below theupper critical or A3 temperature in a reducing, non-oxidizingatmosphere.r The iron or low carbon steel must be maintained in thealpha phase but, because of the loss of carbon in the decarburizingstep, the upper critical temperature or A3 temperature is then about1650'J F. A temperature of about 1550a F. will be sufficient if the timeat temperature is forty-eight hours or more. A preferred temperaturerange is about 1600 F. to about 1650 F. and with such a restrictedtemperature range the time at temperature may be less than twentyfourhours.

With the development of open coil annealing, it is possible toaccomplish decarburizing, denitriding and the final annealing steps in asingle furnace by changing the temperatures and atmospheres in the sameWay as when a strand anneal is followed by a box anneal.

A high degree of preferred orientation can be achieved in the ingot ironor low carbon steel by causing sulfur to be diffused into the grainboundaries of the primary grains, thus restricting their growth andmaking possible a secondary recrystallization -withselectivefgraingrowth. This is accomplished by treatment of the ingotiron or low carbon steel with sulfur or sulfur compounds at final gaugeand immediately prior to or during the primary grain growth portion ofan anneal. There are various ways in which this can be done.

The invention can be practiced by the addition of ferrous sulfide orother sulfur compounds, which dissociate or decompose at thetemperatures of primary grain growth, to the annealing separatoremployed during the final heat treatment. Elemental sulfur can also beadded to the separator for the same purpose,

The preferred annealing separators are magnesia, alumina or calciumoxide or mixtures of these in finely divided form although othersubstances may be used, if desired, such as titania and other refractorymetal oxides.

The final anneal which may include both a primary recrystallization anda secondary recrystallization is usually an anneal in dry hydrogen in amufiie or box. The anneal may be carried on with the material in theform of stacked sheets or wound coils; and if the'atmosphere of theannealing is required to act upon the ingot iron or low carbon steel,excellent results may be obtained by annealing in loose coils formed inaccordance with modern techniques. Whether or not the material exists assheets in a stack or as convolutions of a coil, it is preferred that thequantity of the sulfur-bearing material at the surfaces of the stock bemaintained within certain limits as later set forth. It is believed thatthe sulfur or sulfur compound reacts with the dry hydrogen annealingatmosphere to form hydrogen sulfide; that the sulfur is transferred tothe steel by means of hydrogen sulfide as a carrier; and that thehydrogen sulfide reacts with the steel to form sulfides at the grainboundaries. The reaction occurs while the furnace temperature is betweenabout 1000 F. and 1650 F. The absorption of sulfur creates high sulfurconcentrations at the grain boundaries of the primary structure tendingto prevent the primary grain structure from undergoing such grain growthas would interfere with subsequent secondary recrystallization. Thus afinely grained matrix is maintained until secondary grains of thepreferred orientation begin to consume the grains of other orientations.Thereafter as the temperature rises further, secondary grain growth willproceed by grain boundary energy and will convert the fine grain matrixinto a well developed structure of preferred orientation.

It follows from the explanation that instead of including sulfur or asulfur-bearing compound in the annealing separator, comparable resultsmay be achieved by charging the annealing atmosphere with hydrogensulfide or any other gaseous sulfur compound, such as sulfur dioxide,sulfur hexafluoride and the like, which would react at the grainboundaries at temperatures around or slightly above 1000 F. This may bedone during the primary grain growth period which occurs during theheating of the material up to the temperature at which secondaryrecrystallization occurs in a final anneal. Selenium or hydrogenselenide will behave similarly to sulfur or hydrogen sulfide, althoughthese substances are more expensive, and these materials are to lbeconsidered the equivalents of sulfur and hydrogen sulfide.

In yet another variant procedure, the sulfur or sulfur-bearing compoundmay be made available at the surfaces of the sheet material during adecarburizing anneal prior to the final anneal. For example, if theingot iron or low carbon steel strip is moved through an elongatedfurnace containing a special atmosphere for removing carbon, it ispossible to mix hydrogen sulfide with the decarburizing atmosphere toform a controlled iron sulde film on the material which will inhibit theprimary grain growth which continues during the subsequent final anneal.

The amount of elemental sulfur or sulfur in the form of a sulfur-bearingcompound added to the annealing separator may be from about 1/2% toabout 10% of the annealing separator by weight, when the separator isapplied in a quantity of about ten pounds per ton of ingot iron or lowcarbon steel. It has been found that secondaries produced over thisrange of sulfur additions show a tendency to become larger as the sulfuraddition is increased. The quantity of sulfur made available to theingot iron or low carbon steel may exceed the solubility of sulfur inthe area of the grain boundaries. Some sulfur will be lost during thedrying of a slurry coating and the handling of the dried coating.Therefore it is necessary to add sufficient excess to make up for thisloss, and values disclosed refer in all cases to the amount of sulfur orsulfide present during the heat treatment.

As has been indicated hydrogen sulfide or other sulfurbearing gas may beadded to the annealing atmosphere in lieu of including sulfur in theannealing separator. Where this is done, and assuming that theatmosphere has access to all surfaces of the ingot iron or low carbonsteel, at least 750 p.p.m. of hydrogen sulfide or its equivalent shouldbe present in the atmosphere. It is possible, however, to add largerquantities of sulfur-bearing gases, even to the extent of forming aniron sulfide film or surface layer as taught in the copendingapplication of the same inventor, Ser. No. 378,823, filed .Tune 29,1964, now Patent No. 3,333,992. Where the ingot iron or low carbon steelis given a heat treatment such as a decarburizing treatment precedingthe final heat treatment, the sulfide film is formed ahead of the finalanneal and the sulfides will diffuse into the primary grain boundariesduring the final anneal.

The total sulfur content of the ingot iron or low carbon steel is notnecessarily controlling. The presence of finely dispersed sulfides atthe grain boundaries during the final anneal is of primary importance.It follows that a low carbon steel or ingot iron having sufficientsulfides at the grain boundaries may be suitable for primary andsecondary grain growth even though its total sulfur content may berelatively low, whereas a treatment which tended to remove sulfides atthe grain boundaries might impair the ability of the material to acquirea high degree of preferred orientation even though it did notappreciably lower the total sulfur content of the material.Consequently, the practice of this invention involves the addition ofsome sulfur or sulfide to the ingot iron or low carbon steel after ithas been rolled to final gauge, substantially irrespective of its totalsulfur content, especially since the sulfur or sulfide added by theprocedures herein taught occurs primarily at the grain boundaries.

The properties of the iron or `steel can be damaged by too much sulfur.While limited quantities can be removed at annealing temperatures below1650 F., normally the sulfur is not substantially lowered.

When an iron sulfide film is formed on the surfaces of metal as bymixinghydrogen sulfide with the decarburizing atmosphere, the layer of ironsulde should be about .02 mil to about .10 mil thick.

The use of vacuum annealing is not precluded in the practice of thisinvention. Also nitrogen or other inert gases` may be used with orwithout hydrogen or in a partial vacuum. Sulfur is apparently capable ofdirect diffusion into the metal from the annealing separator.

EXAMPLE I.--A SINGLE STAGE PROCESS FOR MAKING A (112) [110] TEXTURELadle analysis Percent Carbon .010 Manganese .965 Sulfur .025

The process steps 3,392,063 7 8 The material was coated with 8% sulfurin magelemental sulfur, and box annealed at 1630 F. .for 24 nesia. l thours.

TABLE Iv Final Percent Permeability Core Loss, watts/lb. Gauge Cold atH=10 Reduction oersteds P10; 60 P15; 60 P17; 60

(6) The material was box annealed at 1620 F. for The outstanding coreloss values of the materials of sixteen hour in a dry hydrogenatmosphere. the present invention are more pronounced at high fre- Theend product displayed a strong (112) [110] textquencies. Tests of thematerials of Examples IX and XI ure and very good forming properties.were made at `a frequency of 400 cycles per second and at inductions of10, 15 and 17 kilogausses. The results EXAMPLES H and In are summarizedin Table V.

The following Table II gives the final gauge, percentage TABLE Vreduction, type of processing, magnetic characteristics and the type oforientation achieved for five different Core L0ss,wattS/lb samples. Allof the samples were taken from the same P10;400 P15; 400 P17; 400 hotrolled coil as that used in Example I. EX IX 17 47 65 The low carbonsteel was then cold rolled, decarburized Ex. XI 11 25 33 in a stripanneal at l500 C., coated with magnesia containing 4% elemental sulfurby weight, and box an- 25 It can readily be seen from Tables 1V and Vthat the nealed at 1630 F. for 24 hours. permeability and core lossvalues of the materials .were

` TABLE 1r Final Percent Type Permeability 'I ype of Gauge ColdProcessing at H=10 Orlentatioii Reduction oersteds Ex. II .017 83 Singlestage. 1, 820 Cube-on-edge secondarles.

Ex. IIL- .015" 70-1-50 Two stage*l 1, 762 Do.

*The material was reduced 70% in the first stage of cold rolling to anintermediate gauge of .030 and in the second stage to the nal gauge of.015".

EXAMPLES IV, V AND VI found to be exceptionally good, indicating that awelldeveloped cube-on-edge orientation was obtained in all of thesamples.

40 In FIG. 8, the DC magnetization curves for the ma- Percent terials ofExamples VII, VIII and IX are compared t0 Another group of samples wastaken from an ingot iron heat having the following ladle analysis:

Carbon .015 the DC magnetization curves for conventional ingot iron,Manganese .052 non-oriented silicon steel and oriented 3% silicon-iron.It Sulfur 022-. will be obvious from FIG. 8 that the ingot iron of theThe m ate [i a1 was hot rolled to a thickness of 1001, 45 presentinvention requires considerably less magnetizing and finished at atemperature. about 1500@ R The .force to reach the saine induction ascommercial ingot hot rolled band was normalized in a strip furnacel atiron and non-oriented silicon steels. At magnetizing forces of about 1oersted and higher the ingot iron of the present invention comparesfavorably with the more expensive oriented 3% silicon-irons.

The effective sulfur content in the environment of the steel should bemaintained during the primary grain growth period until the temperatureof the steel reaches about 1500 to 1600 F. When this is done graingrowth will be satisfactorily inhibited and the grains having the 1800F. and pickled. After cold rolling various amounts in a single stage asshown in Table III below, the material Was decarburized at 1500 F.,-coated with mag- 50 nesia containing 4% elemental sulfur, and boxannealed for 24 hours at 1600 F. The permeability at all gauges Wasexcellent, indicating that the product had a high degree of cube-on-edgeorientation.

TABLE III preferred orientation will be freed to take over and con-Percent Cold Permeability at trol the final orientation of the productsduring secondary Final Gauge Reduction H=10 Gersteds growth. Generallyspeaking, the amount of sulfur used ef- 025 62 1, 885 fectively in thepractice of this invention may be stated .014" 79 1,392 1 .011/l s31,335 60 as fo lows (1) Where elemental sulfur such as yellow powder orflowers of sulfur is added to an annealinu separator, about EXAMPLES VHTHROUGH XII 1/2% to about 10% sulfur is used, baszd on the weight Themagnetic proper-ties of material processed in the percent of the coatingwhen the coating is used in normal manner of the invention were alsodetermined for ingot 65 thicknesses for annealing separation. ironsamples having the following ladle analysis: (2) Where ferrous sulfideis used to provide the sul- Peprnt fur, the annealing separator shouldcontain about %O% Carbon '020 to 1% of this compound.

(3) Where hydrogen sulfide is added to a decarburizing Manganese .045atomsphere to form a film of iron sulfide to control pri- Sulfur .023

mary grain growth 1n a subsequent anneal, the treatment The material washot rolled to a thickness of .065" should be so regulated to form asulde film having a and normalized at 1800 F. in a strip furnace. Afterthickness of about .0001 (.1 mil) to about .0000.2" (.02 pickling,samples were cold reduced to six final gauges, mil),

decarburized for five minutes at 1500 F. in wet hydro- 75 (4) In anyevent, and whether or not sulfur is added gen, coated with a slurry ofmagnesia containing 21/2% to form an iron sulfide film, or whether ornot sulfur is added during the primary grain growth portion of a finalanneal, the addition being made to either the annealing atmosphere or toan annealing separator, or both, best results are obtained when thequantity of sulfur so added is such as to raise the sulfur content ofthe ingot iron or low carbon steel by no more than about .005% and notless than about .001% by the time the steel has reached a temperature ofabout 1600u to 1650 F. in the final anneal.

It has further been determined that a high manganese content of the lowcarbon steel or ingot iron makes it necessary to increase the sulfuraddition to the annealing separator in order to obtain the -bestsecondary growth. For this reason the managanese content shouldpreferably be less than about .2%.

As will be evident from the above examples, differences in the treatmentof the ingot iron or low carbon steel will largely determine whether acube-on-edge or some type of cube-on-corner or a mixture of the two isobtained in the final product. FIG. 6 is a pole figure illustrating theorientation of the material of Example VII. It will be seen that thepattern indicates unmistakably a high degree of 110) [001] orientation.

FIG. 7 is a pole figure illustrating the orientation of the material ofExample VI and it will lbe seen that the pattern shows a high degree of(112) [110] orientation.

The grain size of the materials of this invention in final form arerelatively large. While the A.S.T.\M. standard chart of grain sizescontemplates a magnification of 100x, the grain sizes of the materialsof this invention can be compared at unit magnification with theS.D.T.M. chart, and as so compared generally respond to No. 8 to No. andeven larger. Moreover, the grains have generally a length at least aboutten times the thickness of the sheet stock.

As above indicated the production of a (112) [110] orientation in ingotiron or low carbon steel substantially increases the formability of theproduct despite a relatively large grain size.

It will be understood that modifications may be made without departingfrom the spirit of the invention, and no limitations are intended otherthan as specifically set forth in the claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method of producing ingot iron and low carbon steel sheet stockcharacterized by a preponderant orientation chosen from a classconsisting of (110) [001] and (112) [110], fwhich comprises hot rollinga ferrous material containing up to 0.10% carbon, 0.01% to 0.40%manganese, up to 0.05% sulfur, the balance being iron except forincidental impurities, to produce an intermediate gauge hot rolled band,cold rolling the said hot rolled band to produce a cold rolled stock atfinal gauge, subjecting said cold rolled stock to a nal anneal duringwhich primary grain growth occurs in the presence of .a material chosenfrom the class consisting of elemental sulfur, selenium, anddecomposable compounds thereof, and thereafter subjecting said stock toa secondary recrystallization treatment under box annealing conditionsat a higher temperature of 1500 to 1650 F.

2. The process claimed in claim 1 in which said iron and steel containsup to 1.8% silicon.

3. The process claimed in claim 1 wherein the said cold rolled stock issubjected to a decarburization treatment prior to said final anneal.

4. The process claimed in claim 1 in which the hot rolling of said lowcarbon steel is finished at a temperature in excess of about 1600 F.

5. The process claimed in claim 1 including a normalizing strand annealfollowing the hot rolling to obtain a uniform fine-grain structure.

6. The process claimed in claim 1 wherein a cold rolling reduction of atleast is used to reduce the material to final gauge and in which theorientation produced in the stock is primarily (112) [110] by Millersindices.

7. The process claimed in claim 1 wherein a cold rolling reduction ofless than 90% is used to reduce the material to final gauge and in whichthe orientation produced in the stock is primarily [001].

8. The process claimed in claim 1 wherein two cold rolling reductionswith an intervening anneal are used to reduce the material to finalgauge, said intervening anneal being a strip anneal.

9. The process claimed in claim 1 wherein sulfur is added to the stockduring the primary grain growth portion of said final anneal.

10. The process claimed in claim 3 wherein said stock is exposed tosulfur from an external source during the said decarburization treatmentto the extent of producing on the stock a thin film of ferrous sulfide.

11. Ingot iron and low carbon steel sheet stock characterized by apreponderant (112) [110] orientation.

12. Ingot iron and low carbon steel sheet stock characterized by apreponderant orientation chosen from a class consisting of (110) [001]and (112) [110] and wherein the grains have a length of at least aboutten times the thickness of said sheet stock.

References Cited UNITED STATES PATENTS 6/ 1942 Carpenter 148-111 OTHERREFERENCES Magnetisch anisotropes Weicheisen, Neve Hutte, Heft 9,September 1963 (pp. 552-556).

1. A METHOD OF PRODUCING INGOT IRON AND LOW CARBON STEEL SHEET STOCKCHARACTERIZED BY A PREPONDERANT ORIENTATION CHOSEN FROM A CLASSCONSISTING OF (110) (001) AND (112) (110), WHICH COMPRISES HOT ROLLING AFERROUS MATERIAL CONTAINING UP TO 0.10% CARBON, 0.01% TO 0.40%MANGANESE, UP TO 0.05% SULFUR, THE BALANCE BEING IRON EXCEPT FORINCIDENTAL IMPURITIES, TO PRODUCE AN INTERMEDIATE GAUGE HOT ROLLED BAND,COLD ROLLING THE SAID HOT ROLLED BAND TO PRODUCE A COLD ROLLED STOCK ATFINAL GAUGE, SUBJECTING SAID COLD ROLLED STOCK TO A FINAL ANNEAL DURINGWHICH PRIMARY GRAIN GROWTH OCCURS IN THE PRESENCE OF A MATERIAL CHOSENFROM THE CLASS CONSISTING OF ELEMENTAL SULFUR, SELENIUM, ANDDECOMPOSABLE COMPOUNDS THEREOF, AND THEREAFTER SUBJECTING SAID STOCK TOA SECONDARY RECRYSTALLIZATIION TREATMENT UNDER BOX ANNEALING CONDITIONSAT A HIGHER TEMPERATURE OF 1500* TO 1650*F.